Field of the Invention
The present invention relates to a printing system that is improved in sheet discharge processing, and more particularly to a technique that copes with, when a sheet processing apparatus becomes incapable of discharging sheets to a sheet discharge destination to make a printing apparatus incapable of performing print processing, a cause of the incapability of discharging sheets by an easy operation, to thereby cause the print processing to be restarted.
Description of the Related Art
A printing system that performs high-productivity high-efficiency printing such as POD (Print on Demand) is comprised of a large-scaled printing apparatus and various sheet processing apparatuses. As a sheet processing apparatus, there has been conventionally used a so-called stacker for stacking a large amount of printed products (printed sheets). By using the stacker, it is possible to perform continuous print processing, and thereby increase productivity.
There has been conventionally proposed, for example, a technique of automatically performing processing for immediately conveying a printed product from a stacker whenever a print job (hereinafter abbreviated to the “job”) is completed (see Japanese Patent Laid-Open Publication No. 2007-219495). Further, there has been proposed a technique of controlling, when one of a plurality of stackers connected to a printing system becomes full, whether to cause sheets to be stacked on the other stacker or stop printing (see Japanese Patent No. 5079147). With these techniques, it is possible to more flexibly and continuously stack a large amount of printed products in the POD environment. Further, in a printing environment in which a plurality of stackers are shared by a plurality of operators, by allowing each operator to continue to use only one stacker, it is possible to prevent printed products to be handled by the other operators from being mixed in the operator's own printed products. Further, in a printing environment in which one operator exclusively uses a plurality of stackers, by configuring such that printed products are continuously output in a manner across the plurality of stackers, whereby it is possible to continuously perform printing over a longer time period.
On the other hand, in a printing system equipped with a plurality of stackers, in a case where each stacker is full of printed products stacked thereon, it is difficult for the operator of the printing system to determine the order of taking out printed products from the stackers. To cope with this, there has been proposed a technique of dividing sheet discharge devices into groups, for each input device for inputting a job or for each operator, and displaying input devices from which jobs were input for respective discharged printed products and each discharge device onto which sheets of each printed product were first discharged, in combination with each other (see Japanese Patent Laid-Open Publication No. H02-193865). By using this technique, in an environment in which one operator performs all of the operation sequence from inputting of a job to conveying of a printed product to a working apparatus used in the next step, even if a stacker from which the printed product is to be taken out is different each time, it is easy to determine a stacker from which the printed product should be taken out. Therefore, it is possible to reduce the possibility of making a mistake in selecting the printed product to be taken out.
However, in an environment, such as a POD environment, in which a large amount of printed products is continuously output, using stackers shared by a small number of operators, even if printed products to be taken out are displayed for each input device or for each operator, the advantageous effect thereof is small. Further, in the POD environment, there can be a case where a user who inputs jobs is a different person from a conveying operator who conveys the printed products of the jobs, and further there are a plurality of conveying operators. In this case, even when the order of taking out printed products is displayed, based on a time at which each printed product was output, for each user who input each associated job, it is difficult for each conveying operator to recognize a conveying order of printed products which he/she should convey, and hence there is a possibility that the operator makes a mistake in selecting the printed product to be taken out by him/her.
Further, even in a case where jobs are input by one user, independently of a job having caused a state of being tray-full i.e. a state in which a sheet discharge destination is full and is no longer able to receive discharged sheets, an irrelevant job could be sometimes executed earlier to cause a printed product of the irrelevant job to have been discharged in a discharge tray which is made tray-full by the first-mentioned job. In this case, even when the order of priorities of the printed product to be taken out is displayed only based on the output order, it is difficult for the user or the conveying operator to recognize which printed product should be taken out first. For example, a case can be envisaged where after a large amount of printed products is output earlier to a stacker which is a sheet discharge destination, a tray for stapling becomes tray-full during execution of a job set to stapling for a small lot. In this state, if the operator desires to continue the job set to stapling, it is necessary to immediately take out the printed product on the tray for stapling, but a warning (instruction) is displayed for taking out the printed products on the stacker, earlier in printing order, which causes the user or the conveying operator to misidentify a priority operation to be preferentially performed.